Abstract

Modeling of Temperature Field in Tissue Created by Therapeutic Phased Arrays with Regular and Random Distribution of Elements

E.Filonenko, V.A.Khokhlova (Department of Acoustics, Faculty of Physics, Moscow State University, Moscow, Russia); L.R.Gavrilov (Andreev Acoustics Institute, Moscow, Russia.)

e-mail: lena@acs366b.phys.msu.su; vera@acs366b.phys.msu.su

Numerical algorithms for modeling of arbitrary three-dimensional acoustic and temperature fields in biological tissue are developed. Spatial distributions of acoustic intensity and temperature patterns in tissues created by two-dimensional therapeutic phased arrays with regular or random distribution of circular elements on a spherical shell are investigated. Generation of single focus or multiple foci are considered. The occurrence of secondary maxima of the intensity in the acoustic field and corresponding hot spots in the tissues are analyzed, when the focal region or several foci are moved along the axis and in the transverse direction. The possible role of nonlinear effects on the temperature rise is analyzed for the cases of generation of single focus or multiple foci, real parameters of phased array systems and biological tissues. It is shown that the random distribution of elements on the surface of the array eliminates the appearance of grating lobes and undesirable overheating of some regions of tissues as compared with regularly distributed elements. The use of different modes of the phased array operation enables to increase or decrease the ablative effect of ultrasound on the tissues. Work is supported by RFBR and CRDF.

Section : 5